Adding interface to register multiple direct functions
within single call. Adding following functions:

  register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
  unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

The register_ftrace_direct_multi registers direct function (addr)
with all functions in ops filter. The ops filter can be updated
before with ftrace_set_filter_ip calls.

All requested functions must not have direct function currently
registered, otherwise register_ftrace_direct_multi will fail.

The unregister_ftrace_direct_multi unregisters ops related direct
functions.

Link: https://lkml.kernel.org/r/20211008091336.33616-7-jolsa@kernel.orgSigned-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>